Hi All

A bit of history on MagLev/Mass-drivers/electromagnetic launchers. Arthur C. Clarke is one of the earliest SF writers to use mag-lev in his stories - beaten by Robert Heinlein's "Future History" [written 1940s-50s] stories which launched chemical rockets up Pike's Peak on a mag-lev.

1949: Earth space-cruiser armed with "electromagnetic guns" [what are now known as "rail-guns"] in "Hide and Seek"

1949: Mag-Lev launches his atomic moonship "Prometheus" from Woomera, Australia.

1951: Fuel launched from Moon to orbitting vehicles in "Islands in the Sky"

1959: Manned Lunar mag-lev using water-filled cabin to counter-act high gees in "Descent into the Maelstrom".

Hence "mag-lev" is not a new idea. It's essentially a linear electromagnetic motor - the "rotor" ["lineor???"] moves quickly along the stator, rather than spinning.

A "lunatron" - as one writer called it - needs to reach 2,375 m/s to escape the Moon. By the kinetic energy equation that's 0.5 x (2375)^2 J/kg = 2.82 MJ/kg. Via the work equation/mass we get, W/m = F/m*s = a*s. Hence an acceleration of 3 gee [3*9.8 m/s^2 = 29.6 m/s^2] needs a track 95.3 km long. A twenty-gee track is 14.3 km long, and a hundred gee track "just" 2.86 km.

Escape velocity is preferred because the perilune of a maglev payload shot into orbit terminates at the altitude of the maglev if launched horizontally, and under the ground at any other angle. Unless a small rocket circularises the payload at some suitable orbit.

Adam

PS I have a new Blog at...

http://crowlspace.blogdrive.com/